English: This image shows the interior of one of the four 8.2-metre Unit Telescopes at ESO’s Very Large Telescope (VLT) in Paranal, Chile. Designated Unit Telescope 1, or UT1, and named Antu, this complex science machine has been in operation at Paranal since 1999. Just before sunset, technicians retract UT1’s windshield and work to finalise the preparations at the telescope for the night-time observation run. During the day, the enclosure is kept shut to protect the delicate and valuable scientific equipment inside, as well as to ensure minimal temperature differences between the telescope and the atmosphere at opening. To the left of the telescope’s main mirror housing, in the centre of the image, is the Infrared Spectrometer And Array Camera (ISAAC), which was, until recently, attached to this instrument. It has now been moved to another of the Unit Telescopes, UT3 or Melipal.